The present invention relates to apparatus for encoding information on webs or strips, especially on webs or strips having layers consisting of photosensitive material, and more particularly to improvements in apparatus for applying printed matter to webs or strips which are moved stepwise through a photographic copying machine. Still more particularly, the invention relates to improvements in apparatus for applying printed matter to the rear sides of successive frames of a web or strip of photographic paper.
The commonly owned U.S. Pat. No. 3,165,988 to Wick et al. discloses an apparatus wherein wheel-shaped holders of symbols are mounted on the continuously driven shaft of a transmission and each holder receives torque from the shaft through the medium of a discrete friction clutch. When a selected symbol on a given holder is moved adjacent to a ribbon which is placed between the holders and the rear side of a web of photographic paper, a pawl engages and arrests the corresponding holder. Once the selected symbols of all holders are adjacent to the web, the latter is pushed against the ribbon by a pressure plate so that the selected symbols transfer ink from the ribbon onto the rear side of the web. Selected symbols are moved adjacent to the ribbon in response to depression of corresponding keys on a keyboard. The symbols can represent the extent to which the photosensitive layer of the web of printing paper is exposed to light of a given color or other data which should be recorded or encoded prior, during or subsequent to reproduction of the image of an original.
A drawback of the just outlined apparatus is that it is prone to malfunction, especially in view of the fact that it employs several friction clutches. Moreover, and since all of the clutches are continuously driven by the output shaft of the transmission, the wear upon the clutches is extensive and the inspection, repair and/or replacement of parts invariably entails length interruptions in operation of the copying machine.